Language bindings have so far been unable to implement the GListModel
interface because the ::get_item virtual function returns a
non-bindable type (gpointer). The `gpointer` type gets translated into
`void` by G-I meaning that get_item() implementations can't return any
items.
We can set the return type of the get_item() vfunc explicitly to
GObject, which fixes the issue.
This patch also removes the existing (type GObject) annotation on
g_list_model_get_item(), which is necessary because if its return type
matches that of the get_item() vfunc, G-I connects the two and
propagates the 'skip' annotation from one to the other resulting in the
get_item() vfunc being hidden. There's no API break here because the
'skip' annotation makes g_list_model_get_item() invisible to G-I users
anyway.
https://bugzilla.gnome.org/show_bug.cgi?id=787271
It's unnecessary, and only adds visual noise; we have been fairly
inconsistent in the past, but the semi-colon-less version clearly
dominates in the code base.
https://bugzilla.gnome.org/show_bug.cgi?id=669355
GListModel is an interface that represents a dynamic list of GObjects.
Also add GListStore, a simple implementation of GListModel that stores
all objects in memory, using a GSequence.
https://bugzilla.gnome.org/show_bug.cgi?id=729351
